In the past year the Mucosal Immunity Section has been engaged in a number of research studies involving both inflammatory bowel disease and common variable immunodeficiency. In the area of inflammatory bowel disease we have completed collaborative studies with the University of Maryland being conducted under a Bench-to-Bedside Grant. The purpose of these studies was to identify differences in the immunologic response of patients undergoing initiation of anti-TNF-alpha therapy who are clinically responsive or not responsive to this therapy. We have enrolled 10 patients in this study and in each case have conducted studies of peripheral mononuclear cells to determine changes in cytokine secretion resulting from treatment with anti-TNF-alpha. In virtually all cases, treatment resulted in lamina propria mononuclear cells that secreted increased amounts of IL-10 compared to cells obtained from patients prior to treatment. This finding may explain the therapeutic effect of anti-TNF-alpha therapy, but additional studies of cells isolated from patient intestinal tissue will be necessary to more firmly establish this possibility. In a second study of inflammatory bowel disease we are assessing safety, efficacy and immunologic effect of infusions of allogeneic bone marrow-derived mesenchymal stromal cells. This study is being performed in collaboration with the NIH Bone Marrow Stromal Cell Transplantation Center in the NIH Transfusion Medicine Department (under the direction of Dr. Pamela Robey) which is preparing the carefully prepared and standardized mesenchymal stem cells that are being infused. In this project both ulcerative colitis and Crohn's disease patients are being studied with respect to mRNA responses determined by microarray as well as with respect to induction of regulatory T cells. This project has been approved by the NIAID IRB and we have so far enrolled two patients in the program, both with Crohn's disease. In a third study of inflammatory bowel disease we are collaborating with Dr. Harry Malech and his colleagues (Dr. Suksee DeRavin) in on-going studies of Crohn's disease-like colitis occurring in patients with chronic granulomatous disease (CGD). These studies include the evaluation of cytokine production in the inflamed mucosa of CGD patients. The goal of this study is to discover differences and similarities between Crohn's disease in CGD patients and in conventional patients. In the studies conducted so far, Crohn's disease in CGD patients and conventional patients appear to be quite similar. This has led us to conclude that CGD is, in effect, a risk factor for the development of Crohn's disease. In on-going studies we are collaborating with Dr. Steven Brant. a geneticist at Johns Hopkins University Medical Center, to define genetic polymorphisms in patients with CGD that have been associated with Crohn's disease. In a fourth study of inflammatory bowel disease we have focused on the immunologic properties of lamina propria cells in patients with ulcerative colitis. Previous studies have shown that ulcerative colitis (UC) is associated with the presence of lamina propria non-invariant (Type II) NKT cells producing IL-13 and mediating epithelial cell cytotoxicity. Using cells derived from biopsies of UC patients under evaluation at NIH and elsewhere, we sought to define the antigen(s) stimulating such cells and to quantitatively assess these cells in the lamina propria. Our studies showed that UC lamina propria is replete with Type II NKT cells responsive to lyso-sulfatide glycolipid and bearing IL-13Ra2. Since lyso-sulfatide is a self-antigen these data suggest that an autoimmune response is involved in UC pathogenesis. Dr. Michael Yao, now a gastroenterologist at the Washington VA Medical Center, will collaborate with us in studies of UC patients with a range of severity to determine the relation of the level of intestinal infiltration of NKT cells responsive to lyso-sulfatide and disease course and severity. In the area of CVID we have continued to focus on gastrointestinal manifestations of the disease. In priorr studies of CVID we established that the CVID GI syndrome is driven by cells producing IFN-gamma. In addition, we collaborated with Drs. Andriy Morgan and Natalia Stolzhenko in the Laboratory of Cellular and Molecular Immunology in studies of CVID that included microarray analyses of biopsy tissue of CVID patients with enteropathy showing that CVID enteropathy is characterized by up-regulation of genes related to type 1 interferon. Based on this prior work, we have applied for a U01 NIH cooperative research grant (PAR-13-029) with Drs. Morgun and Shulzhenko now at Oregon State University to expand on these findings. This Grant, entitled Anti-IL-12p40 Treatment of CVID Enteropathy: Gene Expression and Microbiota Analysis, proposes a clinical study of the safety and efficacy of a FDA-approved monoclonal anti-IL-12p40 in the treatment of CVID enteropathy. It also outlines a study of the effect of this biologic agent on gene expression of inflammatory cytokines and on the microbiota in patients. During this period we have also completed an in-depth study of nodular regenerative hyperplasia (NRH) occurring in a substantial fraction of patients with CVID. NRH is an abnormality observed in a variety of hepatic diseases that is thought to result, at least in part, from an intra-hepatic vasculopathy common to these diseases. The vasculopathy leads, on the one hand to hepatocyte injury and, on the other, to hepatocyte regeneration. The latter results in the formation of characteristic nodules, which compress surrounding hepatic parenchyma as well as the portal and central veins and thus have the potential to cause portal hypertension, esophageal varices and splenomegaly. NRH in our CVID patient population occurred in approximately 5% of the 261 patients in our total CVID study group, initially presenting in most cases with an elevated alkaline phosphatase level. While in some patients the disease remained static, in a larger proportion a more severe disease developed characterized by portal hypertension, the latter leading to hypersplenism with neutropenia and thrombocytopenia and, in some cases, to ascites. In addition, a substantial proportion of patients either developed or presented initially with an autoimmune hepatitis-like (AIH-like) liver disease that resulted in severe liver dysfunction and, in most cases to death due to infections. The liver histologic findings in these AIH-like patients were characterized by underlying NRH pattern with superimposed interface hepatitis, lymphocytic infiltration and fibrosis. Immunologic studies of biopsies of NRH patients demonstrated the presence of infiltrating T cells producing IFN-gamma;, suggesting that the NRH is due to an autoimmune process.Overall, these definitive studies of NRH in CVID provide evidence that NRH can be a severe and potentially fatal disease complication of CVID that merits close monitoring and intervention.